Is 6 Hours of Sleep Enough to Build Muscle? The relationship between sleep and muscle growth.
By Coach Hunter Bennett
Sleep plays a vital role in practically all the physiological processes in your body. This includes muscle growth and recovery. As such, it stands to reason that not getting enough sleep can hinder your progress.
But how much sleep do you really need for optimal muscle growth?
In this article we dive into the effects of sleep on strength performance, muscle recovery, and muscle growth, and ultimately address the question: Is 6 hours of sleep enough to build muscle?
The Effect of Sleep on Strength Performance
As you would expect, poor sleep does have a negative effect on strength, but it is not as large as you might think.
A recent meta-analysis (a study that combines the results of multiple studies) sought to explore this topic in detail, and came to some interesting conclusions.
They found that a single night of poor sleep (ranging from 0-5 hours of sleep) appears to have a small impact on the amount of weight you can lift on complex exercises, such as squats, deadlifts, and the bench press.
However, it does not seem to have any impact on strength on machine-based exercises like leg presses, or isolation exercises like bicep curls.
It is also important to note that this effect does seem to get a little larger with repeated nights of poor sleep. For example, only get 5 hours sleep one night will have a negligible impact on your strength (~3% worse). But if you only get five hours sleep every night for a week, your strength is likely to decline further as the week goes on.
This does indicate that poor sleep (i.e., 5 hours or less) may have an impact on how much weight you can lift in the gym, which might impact muscle growth in the long term – but more on that below.
The Effect of Sleep on Training Volume
While the effect of poor sleep on muscle strength is relatively small, the effect on training volume is more pronounced.
In the same meta-analysis, they found that poor sleep (again, 0-5 hours of sleep) decreases the number of reps you can perform at a given load by about 10%. For example, if you could bench press 100kg 10 times after a good night’s sleep, you might only be able to do it for 9 reps after a bad night sleep.
Although this doesn’t sound huge, it is likely to get worse the more sets you do, which over the duration of session, can end up contributing to notably lower training volume.
The Effect of Sleep on Muscle Recovery
Muscle recovery is a multifaceted process that involves repairing damaged muscle fibres and replenishing energy stores.
Sleep is important in all recovery processes, as it provides your body with time it needs to adapt and repair from the day’s stressors. As such, it makes sense that sleep is integral to muscle recovery after exercise.
However, just how much sleep you need to ensure muscle is currently unclear.
Research in high level rugby athletes has shown that players who get no sleep (i.e., a full night of sleep deprivation) the night after intense exercise have slower recovery rates and greater muscle soreness than those who get a normal (~8 hours) night’s sleep. Similar results have also been seen in cyclists who only got ~3.5 hours of sleep per night.
However, in research on high level soccer players, there was no difference in post exercise recovery and soreness in those athletes who got ~5 hours of sleep compared to those who got ~8 hours.
While this is a small number of studies, it may suggest that in the short-term getting anything less than 5 hours per sleep per night will impact muscle recovery, while anything above that may not.
If you want to learn more about recovery, make sure to check out our article “Are ice baths killing your gains?”
The Effect of Sleep on Muscle Growth
So, we now know that poor sleep can impact our performance in the gym negatively. We also know that severe sleep deprivation can impact our recovery after exercise – but does this impact muscle growth?
To date this is a question that has not been answered directly by the research, but we can look to elsewhere to gain insight into the relationship between sleep and muscle growth.
Firstly, there is evidence demonstrating that a single night of complete sleep deprivation (i.e., no sleep) will cause an ~20% reduction in rates of muscle protein synthesis.
As muscle protein synthesis is how your body produces new muscle tissue, this implies that sleep restriction may impact muscle growth.
Secondly, there is some research showing that getting less than 5 and half hours of sleep may increase loss of lean mass retention during times of caloric restriction compared to getting 7 or more hours, suggesting sleep may help maintain muscle mass.
Lastly, we know (as outlined above) that poor sleep can decrease the amount of weight you can lift and the number of reps that you can perform. This is going to cause a notable reduction in training volume.
As muscle growth is directly linked to the amount of training volume you perform (at least up until a point), this may have an impact on how stimulative your workouts are.
Collectively, this research does suggest that poor sleep might have an impact on muscle growth.
However, to what extent is likely determined by just how much sleep you get (or don’t get…).
Is 6 Hours of Sleep Enough to Build Muscle?
Most sleep guidelines suggest that adults aged 18-64 aim for 7-9 hours of sleep per night to maintain health and well-being.
Given there is a strong link between health and performance, it seems feasible that adhering to this range is also likely to lead to the best long-term improvements in muscle growth.
However, it is important to note that most of the research above only shows a negative effect when people sleep less than 5 hours, with the most notable effects coming after a complete night of no sleep.
All of which is to say that if you are getting six hours of sleep per night, it may not be having a meaningful impact on your long-term progress. And if this happens once or twice per week, it is very unlikely it is having any effect at all.
Optimizing Sleep for Muscle Building
Now, if you are consistently getting less than 5 or 6 hours of sleep per night, it might be time to implement some strategies to improve your sleep quality and get you a little closer to that 7–9-hour range.
- Consistency: Maintain a consistent sleep schedule by going to bed and waking up at the same times each day, even on weekends.
- Create a Restful Environment: Ensure your sleep environment is conducive to rest. Keep the room dark, quiet, and at a comfortable temperature.
- Limit Screen Time: Reduce exposure to screens (phones, tablets, computers) before bedtime, as the blue light emitted can interfere with melatonin production, a hormone crucial for sleep. Try and steer clear of screens for the 60m before bed.
- Limit Caffeine In the Afternoon: Caffeine is a stimulant that is known to impact sleep. It also has a half life of ~8 hours for most people, suggesting you should limit your intake after lunchtime to minimise its effects.
Conclusion: Is 6 Hours of Sleep Enough to Build Muscle?
Severe sleep restriction can impact your performance and tour recovery. However, this effect only appears to be notable when you get 5 hours of sleep or less.
With this in mind, a couple of nights of poor sleep every now and then are unlikely to have any impact on long-term muscle growth. However, constantly getting less than 6 hours per night might start to slow your rate of progress.
If you are someone who struggles to sleep and regularly gets less than 6 hours per night, using the tips outlined in this article can boost sleep quality and keep you making gains.
Has your progress stalled? If you want to bust through a plateau, make sure to check out our programs.